Factors influencing patch occupancy and within‐patch habitat use in an apparently stable population of Willow Tits Poecile montanus kleinschmidti in Britain

Abstract

Capsule Birds selected younger woodland patches with fewer conifers and higher soil moisture content; within these patches, they selected areas with higher vegetation cover at 2–4 m, and less bracken. Aims For an apparently stable population, to investigate habitat differences between occupied and unoccupied woodland patches and habitat selection within occupied woodlands. Methods We surveyed woodland patches for breeding Willow Tits in April 2006 in an area with an apparently stable population. Habitat was measured at points spread throughout each woodland patch and at points where Willow Tits were located. We compared habitat between occupied and unoccupied sites. In addition, within occupied sites, we examined habitat differences between Willow Tit locations and the points spread throughout the wood. Results We surveyed 65 woodland patches, of which 29 were occupied. Willow Tits were more likely to be found in deciduous woodland that was younger and had higher levels of soil moisture. Probability of occupancy fell from 60% for woods aged 20–25 years to only around 15–30% for woods aged over 80 years. Within occupied woods, Willow Tits were more likely to be found in areas with more vegetation cover at the 2–4 m level and in areas with less bracken. Conclusions Habitat management for Willow Tits should involve provision of young woodland patches with moist soils. Changes to the age structure and/or the soil moisture content of woods may be implicated in the dramatic decline of Willow Tits in Britain.